Cos for mechanical harvest

ABSTRACT

The present invention relates to a  Lactuca sativa  L. var.  longifolia Lam  seed which has a solid main vein and narrow base leaves, dark green outer leaves, short core, absence of fringe burn, and absence of tipburn. A specific embodiment is designated 41-69 RZ, referred to as Actarus. The present invention also relates to a  Lactuca sativa  L. var.  longifolia Lam  plant produced by growing the “41-69 RZ” (“Actarus”) seed. The invention further relates to methods for producing the lettuce cultivar, represented by lettuce variety 41-69 RZ.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a new lettuce (Lactuca sativa) varietywhich is suitable for mechanical harvest.

2. Description of Related Art

Romaine lettuce should provide a product at harvestable stage, which isaccepted by processing industry and/or consumers. Therefore, theharvestable product should not have tipburn, should have a short core,and it should have a dark green outer leaf colour. Further it should besufficiently headed, and as a result of this heading provide sufficientyellow-coloured heart leaves.

Until now mature romaine lettuce is mainly harvested by hand. Thisharvesting process is labour-intensive, and relativelylabourer-unfriendly. As it is getting more and more costly to hirelabourers that want to work outdoor in the field, close to the groundand under all kinds of adverse weather conditions, there is stronginterest of the lettuce industry to mechanize this manual harvestingprocess. However, until now the lack of uniform quality among matureplants is a big problem for mechanised harvest. Poor quality of basalleaves, internal breakdown of heart leaves due to tipburn, fringe burnof leaf margins, and fast bolting are the main quality problems. If onewould like to mechanise the harvest process, these quality problemswould result in additional hand sorting, which is costly, and/or a verylow net yield, if the plant parts with a high risk of quality problemsare mechanically discarded.

The latter approach is chosen by some producers that produce romainehearts, i.e. the intact yellow-green heart of the romaine lettucewithout the green outer leaves. For producers that produce romainelettuce for processing, i.e. pre-washed and pre-cut leaves, this is notfeasible because of three major constraints. The first is therequirement for a mix of green and yellow leaves, which requires thepreservation of the green outer leaves. The second constraint is thestrongly reduced net yield, which is a result of the fact that anautomated knife should cut through the leaf but not through the core.Especially fast bolting lettuce varieties are unacceptable formechanised harvest of romaine lettuce for processing purposes because oftheir long core. The third constraint is caused by the use ofmechanically-driven horizontal knives that easily damage the hollow mainveins of romaine leaves and cut halfway through the prostrate,round-shaped, lower outer leaves, which results in wide cut surfaces.Cutting damage on a leaf with a hollow main vein is often not restrictedto the cut surface but bruising extends into the leaf along the mainvein.

It is the object of the invention to provide a new type of romaine orcos lettuce, which is suitable for mechanical harvest with a simplehorizontal knife. The harvested product is meant for processingpurposes.

SUMMARY OF THE INVENTION

The present invention fulfils this need by providing a new romaine, orcos lettuce (Lactuca sativa L. var. longifolia Lam) plant, whichexhibits a combination of leaves with a solid main vein and narrow baseleaves.

In particular, the present invention provides the Lactuca sativa L. var.longifolia Lam plant with the following additional characteristic: darkgreen outer leaves.

In particular, the present invention provides the Lactuca sativa L. var.longifolia Lam plant with one or more of the following additionalcharacteristics: short core, absence of fringe burn, and absence oftipburn.

More in particular, the present invention provides seeds of the Lactucasativa L. var. longifolia Lam plant designated as 41-69 RZ, referred toas Actarus.

The present invention also provides a lettuce plant or parts thereofproduced by growing the seed of lettuce cultivar 41-69 RZ.

The present invention further provides pollen, ovules, and tissuecultures of regenerable cells from the plant produced by growing theseed of lettuce cultivar 41-69 RZ, in which the cells or protoplasts ofthe tissue that are cultured are produced from a tissue selected fromleaves, pollen, embryos, cotyledon, hypocotyls, meristematic cells,roots, root tips, anthers, flowers, seeds or stems.

The present invention still further provides a lettuce plant regeneratedfrom the above-described tissue cultures, in which the regenerated planthas all of the morphological and physiological characteristics oflettuce cultivar 41-69 RZ.

The present invention also provides a transgene of the seed of lettucecultivar 41-69 RZ.

The present invention further provides a method for producing a hybridlettuce seed comprising crossing a first parent lettuce plant with asecond parent lettuce plant and harvesting the resultant hybrid lettuceseed, wherein the first parent lettuce plant or the second parentlettuce plant is the lettuce plant produced by growing the seed oflettuce cultivar 41-69 RZ.

The present invention still further provides a method for developing alettuce cultivar having leaves with a solid main vein and narrow baseleaves comprising crossing a mother lettuce plant cultivar with a fatherlettuce plant cultivar to produce a hybrid seed; growing the hybrid seedto produce a hybrid plant; selfing the hybrid seed to produce F2 progenyseed; and selecting the F2 plants for having leaves with a solid mainvein and narrow base leaves.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a transverse section at 40% of leaf lamina length toobserve solidness of main vein.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a Lactuca sativa L. var. longifolia Lam(romaine or cos lettuce) plant comprising leaves with a solid main veinand narrow base leaves.

In particular, the present invention provides the Lactuca sativa L. var.longifolia Lam plant with the following additional characteristic: darkgreen outer leaves.

In particular, the present invention provides the Lactuca sativa L. var.longifolia Lam plant with one or more of the following additionalcharacteristics: short core, absence of fringe burn, and absence oftipburn.

In particular, the present invention provides seeds of the Lactucasativa L. var. longifolia Lam plant designated as 41-69 RZ, referred toas Actarus. Seeds of lettuce cultivar 41-69 RZ have been deposited onSep. 20, 2006 with the National Collections of Industrial, Marine andFood Bacteria (NCIMB) in Bucksburn, Aberdeen AB21 9YA, Scotland, UK andhave been assigned NCIMB Accession No. 41440.

As used herein, romaine is Lactuca sativa L. var. longifolia Lam , alsoknown as cos. The plant develops in an upright open or upright compactgrowing habit with coarse textured leafs. The younger leaves are longerthan they are wide, fifteen cupping together to form an elongated loosehead. Leaf margins are often entire or undulated, rarely frilled. Outerleaves range in color from light green to dark green. Inner heart leavesare smaller and range from light yellow to light green in color.

As used herein, a solid main vein is the main vein of a fully growntenth to fifteenth leaf, which is characterised by the fact that thevein is not hollow, which is observed by visual inspection of atransverse section of the leaf. The transverse section should be made at40% of the total leaf length, starting from the leaf base (see FIG. 1).For comparison two standard varieties can be used: Maximus, with hollowveins, and Tiberius, with solid veins.

As used herein, a narrow base leaf is characterised by alength/width-ratio of 1.5 or higher. A mature romaine lettuce plant hasgot narrow base leaves if the average length/width-ratio of the fullygrown tenth to the fifteenth leaf is 1.5 or higher. For comparison twostandard varieties can be used: Maximus with broad base leaves, andChilim with narrow base leaves.

As used herein, dark green outer leaves are defined by the colour of afully grown tenth to fifteenth leaf, which should be similar to ordarker than 137B, 138A, 144A, or 146A on the RHS colour chart (The RoyalHorticultural Society, London, UK).

As used herein, a short core is defined by measuring the length of thecore of a harvested mature plant with outer leaves attached. The plantshould be grown outdoor under long-day conditions: sowing 5-15 daysbefore the longest day in a mild mid-latitude climate with a warm summer(Koppen-classification: Csb or Cfb; McKnight & Hess, 2000. PhysicalGeography: A Landscape Appreciation. Upper Saddle River, N.J.: PrenticeHall). A mature plant grown under these conditions is defined as beingheaded and having a weight of 800-1200 g after harvest. The core of sucha plant is defined as ‘short’ if its length is less than or equal to 8cm.

As used herein, absence of fringe burn is established by growing plantsin outdoor conditions in a winter production area for lettuce with anaverage daily temperature of the coldest month between 11 and 14° C.,for example Cartagena, Spain or Yuma, USA. The growing cycle under theseconditions should be at least 16 weeks from sowing a seed to harvestinga mature plant. Harvesting the mature plant should take place in themonth after the coldest month. Absence of fringe burn is defined byobserving the leaf margin of the tenth until the fifteenth leaf. Absenceof fringe burn is established, if for each of these leaves less than 2%of the perimeter of the leaf margin is necrotic.

As used herein, absence of tipburn is established by growing plants inoutdoor conditions in spring conditions in a winter production area forlettuce with an average daily temperature of the coldest month between11 and 14° C., for example Cartagena, Spain or Yuma, USA. Harvesting themature plant should take place in the third month after the coldestmonth. Absence of tipburn is defined by observing the ten most recentlydeveloped heart leaves longer than 5 cm. Absence of tipburn isestablished, if for each of these leaves less than 1% of the perimeterof the leaf margin is necrotic. The additional requirement forestablishing absence of tipburn is that the comparison variety Maximus,grown under the same conditions with the same sowing and harvest date,shows presence of tipburn, and a second comparison variety Optimus,grown under the same conditions with the same sowing and harvest date,shows absence of tipburn. Presence of tipburn is established, if for atleast one out of the ten most recently developed heart leaves longerthan 5 cm, at least than 1% of the perimeter of the leaf margin isnecrotic.

In an embodiment of the present invention, there is provided a lettuceplant or parts thereof produced by growing the seed of lettuce cultivar41-69 RZ.

In another embodiment, there is provided pollen, ovules, and tissuecultures of regenerable cells from the plant produced by growing theseed of lettuce cultivar 41-69 RZ, in which the cells or protoplasts ofthe tissue that are cultured are produced from a tissue selected fromleaves, pollen, embryos, cotyledon, hypocotyls, meristematic cells,roots, root tips, anthers, flowers, seeds or stems.

In still another embodiment, there is provided a transgene of the seedof lettuce cultivar 41-69 RZ.

In a further embodiment, there is provided a lettuce plant regeneratedfrom the above-described tissue cultures, in which the regenerated planthas all of the morphological and physiological characteristics oflettuce cultivar 41-69 RZ.

In still a further embodiment, a method is provided for producing ahybrid lettuce seed comprising crossing a first parent lettuce plantwith a second parent lettuce plant and harvesting the resultant hybridlettuce seed, wherein the first parent lettuce plant or the secondparent lettuce plant is the lettuce plant produced by growing the seedof lettuce cultivar 41-69 RZ.

In still another embodiment, a method is provided for developing alettuce cultivar having leaves with a solid main vein and narrow baseleaves comprising crossing a mother lettuce plant cultivar with a fatherlettuce plant cultivar to produce a hybrid seed; growing the hybrid seedto produce a hybrid plant; selfing the hybrid seed to produce F2 progenyseed; and selecting the F2 plants for having leaves with a solid mainvein and narrow base leaves.

In a preferred embodiment, the specific type of breeding method employedfor developing a lettuce cultivar is pedigree selection, where bothsingle plant selection and mass selection practices are employed.Pedigree selection, also known as the “Vilmorin system of selection,” isdescribed in Fehr, W., Principles of Cultivar Development, Volume I,MacMillan Publishing Co., which is hereby incorporated by reference.

When pedigree selection is applied, in general selection is firstpracticed among F2 plants. In the next season, the most desirable F3lines are first identified, then desirable F3 plants within each lineare selected. The following season and in all subsequent generations ofinbreeding, the most desirable families are identified first, thendesirable lines within the selected families are chosen, and finallydesirable plants within selected lines are harvested individually. Afamily refers to lines that were derived from plants selected from thesame progeny from the preceding generation.

Using this pedigree method, two parents may be crossed using anemasculated female and a pollen donor (male) to produce F1 offspring.Lettuce is an obligate self-pollination species, which means that pollenis shed before stigma emergence, assuring 100% self-fertilization.Therefore, in order to optimize crossing, a method of misting may beused to wash the pollen off prior to fertilization to assure crossing orhybridization.

Parental varieties are selected from commercial varieties thatindividually exhibit one or more desired phenotypes. Additionally, anybreeding method involving selection of plants for the desired phenotypecan be used in the method of the present invention.

The F1 may be self-pollinated to produce a segregating F2 generation.Individual plants may then be selected which represent the desiredphenotype in each generation (F3, F4, F5, etc.) until the traits arehomozygous or fixed within a breeding population.

The present invention is more particularly described in the followingnon-limiting example, which is intended to be illustrative only, asnumerous modifications and variations therein will be apparent to thoseskilled in the art.

Example 1 Development and Characteristics of Lettuce Cultivar 41-69 RZ

The breeding history of Actarus started in Aramon, France in 1995 with across between a plant from the grasse lettuce cultivar ‘Bambi’ (RijkZwaan) as mother and a plant from the Bremia-resistant indoor bataviabreeding line ‘95A.30955’ (Rijk Zwaan) as father with the aim tointroduce resistance against Bremia lactucae (B1-resistance) in thegrasse type.

An F3-plant, ‘97A.23750’, derived from this cross was selected in July1997 in Aramon, France and used as a father in a cross with a motherplant of the romaine cultivar ‘Fransesca’ (S&G) to introduceB1-resistance in the romaine type. An F3-plant, ‘99A.23056’, derivedfrom this cross was selected in April 1999 in Aramon, France for itsleaves with a solid main vein, its short core, dark green colour,absence of fringe burn and its B1-resistance and used as a father in across with a mother plant of the romaine cultivar ‘Chilim’ (S&G).‘Chilim’ was chosen for its narrow base leaves.

A resulting F1-plant was grown in Aramon, France to produce F2-seeddesignated 00A.47131. This F2-seed was sown in a late summer trial inAramon, France in 2000. In October 2000 an F2-plant was selected forbeing a romaine type with leaves with a solid main vein, a short coreand narrow base leaves. The F2-plant produced F3-seed, designated01A.48557, which was sown in a summer trial in Aramon, France in 2001.In July 2001 an F3-plant was selected from the trial for being a darkgreen romaine type with leaves with a solid main vein, absence oftipburn, a short core, and narrow base leaves. The F3-plant producedF4-seed, designated 02A.50500, which was sown in a winter trial in aplastic tunnel in Aramon, France in 2001. In February 2002 an F4-plantwas selected from the trial for being a dark green romaine type withleaves with a solid main vein, absence of fringe burn and narrow baseleaves. The F4-plant produced F5-seed, designated 02A.51813, which wassown in a spring trial in Aramon, France in 2003. In April 2003 anF5-plant was selected from the trial for being a dark green romaine typeand with leaves with a solid main vein, absence of tipburn, and narrowbase leaves. The F5-plant produced F6-seed, designated 03A.50148, whichwas sown in a late summer trial in Aramon, France in 2003. In October2003 an F6-plant was selected from the trial for being a dark greenromaine type and with leaves with a solid main vein, a short core,absence of tipburn, and narrow base leaves. The F6-plant producedF7-seed, designated 04A.51992, which was sown in an early summer trialin Fijnaart, the Netherlands in 2004. In June 2004 an F7-plant wasselected from the trial for being a dark green romaine type and withleaves with a solid main vein, a short core, absence of tipburn, andnarrow base leaves. The F7-plant produced F8-seed, designated 05A.50606,which was uniform for type, field performance, bolting, absence oftipburn and fringe burn, leaves with a solid main vein and narrow baseleaves (all based on several trials in 2005).

The F8-seed was used to sow a multiplication in Daylesford, Australia inOctober, 2004. The plants showed phenotypical uniformity during seedproduction and seed was harvested for further trialling in 2005 onconfidential sites. The seed lot was designated by the introductionnumber ‘41-69 RZ’ and referred to as ‘Actarus’.

The distinct resistance characteristics of ‘Actarus’ offer a significantadvantage for growers trying to grow romaine lettuce at a low costprice. The variety can be mechanically harvested with standard equipmentfor mechanical harvesting of babyleaf lettuce and/or spinach. Theresulting reduction in harvesting labour is not significantly affectedby the labour required for sorting the harvested product, because piecesof the main core, and leaves with fringe burn or tipburn are virtuallyabsent. Also cutting damage on the main vein of the leaves is minimal,because of the solidness of the vein. The harvested leaves are veryuniform due to the fact that also the older base leaves show a small cutsurface and are longer than they are wide, just like the younger leaves.The dark green colour of the outer leaves provides an attractivecontrast to the more yellow colour of the inner heart leaves.

In the Table that follows, the traits and characteristics of the Lactucasativa L. var. longifolia Lam romaine lettuce plant referred to as“Actarus” and having the designation 41-69 RZ, are given compared to thecomparison varieties mentioned, referred to as “Tiberius”, “Maximus”,“Optimus”, and “Chilim”.

“Actarus” “Tiberius” “Maximus” “Optimus” “Chilim” Character romaine orromaine or romaine or romaine or romaine Type cos cos cos cos or coshollow/ solid solid hollow hollow hollow solid main vein broad/ narrowbroad broad broad narrow narrow base leaves blond/dark dark dark darkblond blond green colour core short long short short long length tipburnabsent present present absent present fringe absent absent absentpresent present burn

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various alterations in form and detail maybe made therein without departing from the spirit and scope of theinvention.

1-62. (canceled)
 63. A method of producing lettuce seed, comprisingcrossing a first lettuce plant, representative seed of which having beendeposited under NCIMB Accession No. 41440, with a second lettuce plant.64. The method of claim 63, wherein the first lettuce plant isdesignated 41-69 RZ, referred to as Actarus.
 65. The method of claim 64,wherein the first lettuce plant has leaves with a solid main vein andnarrow base leaves, dark green outer leaves, short core, absence offringe burn and absence of tip burn.
 66. An F1 hybrid seed produced bythe method of claim
 63. 67. An F1 hybrid plant produced by growing theseed of claim
 66. 68. A method of producing a seed of a 41-69 RZ-derivedlettuce plant comprising the steps of: (a) crossing a lettuce plant of41-69 RZ, a sample of seed of which having been deposited under NCIMBAccession No. 41440, with a second lettuce plant; and (b) allowing seedof a 41-69 RZ-derived lettuce plant to form.
 69. The method of claim 68,further comprising the steps of: (c) crossing a plant grown from the41-69 RZ-derived lettuce seed with itself or a second lettuce plant toyield additional 41-69 RZ-derived lettuce seed; (d) growing theadditional 41-69 RZ-derived lettuce seed of step (c) to yield anadditional 41-69 RZ-derived lettuce plant; and (e) optionally repeatingthe crossing and growing steps of (c) and (d) one or more times togenerate further 41-69 RZ-derived lettuce plants.
 70. A 41-69 RZ-derivedlettuce seed produced by the method of claim 68
 71. A 41-69 RZ-derivedlettuce plant produced by the method of claim
 69. 72. A method ofintroducing a desired trait into lettuce 41-69 RZ comprising: (a)crossing a plant of lettuce 41-69 RZ, a sample of seed of lettuce 41-69RZ having been deposited under NCIMB Accession No. 41440, with a secondlettuce plant that comprises a desired trait to produce F1 progeny; (b)selecting an F1 progeny that comprises the desired trait; (c) crossingthe selected F1 progeny with a plant of lettuce 41-69 RZ, to producebackcross progeny; (d) selecting backcross progeny comprising thedesired trait and the physiological and morphological characteristics oflettuce 41-69 RZ; and (e) optionally repeating steps (c) and (d) toproduce backcross progeny that comprises the desired trait and all ofthe physiological and morphological characteristics of lettuce 41-69 RZwhen grown in the same environmental conditions.
 73. A lettuce plantproduced by the method of claim
 72. 74. A method of producing a plant oflettuce 41-69 RZ, a sample of seed of which having been deposited underNCIMB Accession No. 41440, comprising an added desired trait, the methodcomprising introducing a transgene conferring the desired trait into aplant of lettuce 41-69 RZ.
 75. A progeny plant of the first plant ofclaim 64 that comprises all of the physiological and morphologicalcharacteristics of lettuce 41-69 RZ, a sample of seed of lettuce 41-69RZ having been deposited under NCIMB Accession No.
 41440. 76. A seedthat produces the plant of claim 75.